The joint ring K 43545 is an important sealing component designed for the screw plug K 43544 within the throttle-type non-return valve K 43537 of the Adriadiesel/Jugoturbina/Zgoda/Sulzer ZV40/48 engine starting-air system. Its primary function is to provide a reliable seal between the screw plug and its corresponding seating surface, preventing compressed-air leakage through the threaded closure and helping maintain the required pressure conditions within the valve assembly. The effectiveness of the joint ring depends on its material properties, dimensional accuracy, surface condition, and correct compression during installation, since inadequate sealing can lead to pressure losses, reduced starting-system efficiency, and unnecessary loading of associated components. During service, the K 43545 joint ring may be exposed to repeated pressure fluctuations, temperature variations, vibration, and long periods of operational readiness, making resistance to deformation, deterioration, and loss of sealing capability particularly important. During maintenance or overhaul, the joint ring should be inspected for flattening, cracking, corrosion, surface damage, or other signs of deterioration and replaced when required by the manufacturer's maintenance instructions. By ensuring effective sealing of the K 43544 screw plug, the K 43545 joint ring contributes to pressure integrity, reduced compressed-air leakage, reliable operation of the K 43537 throttle-type non-return valve, and dependable long-term performance of the ZV40/48 starting-air system.